Back when I was in the military (20 years ago) one of our instructors sat us down after a long hard day of field training and discussed fight or flight. He said that 30% of us were going to be totally ineffective on the battlefield due to our genetic makeup. He went on to tell us that all the training in the world cannot flush out, or change the flighter's, and that we won't know who they are until a real mission is upon us, and that even then we may not know, because there are different levels where people are triggered. As a bunch of macho 20 year olds, we thought this was complete b.s. and laughed it off as scare tactics. We were highly trained and we had huge egos, there was no way we were running from a fight.
About six months later we found ourselves in our first gun fight. I have to admit, all the training in the world does not fully prepare you for this. The shear volume and chaos of active gunfire is frightening, the distractions like animals running out of fear, or bark flying off of trees hitting you in the face. You can't prepare for these little details, but eventually your training kicks in and you execute your plan. When the shooting stopped, we discovered what our instructor had told us was true. One of our teammates was sitting in the fetal position, frozen. We thought he had been shot or injured but he was perfectly fine. We felt terrible for him, a few hours later he resigned from our unit. He called himself battlefield ineffective and he apologized to all of us for letting us down. I worked next to this guy for a year in training, and I can tell you he was one tough dude. It was a day of mixed emotions. We finally got the chance to use our training, but we lost one of our own. We didn't lose him to enemy gunfire. We lost him to genetics! Judging by the look on his face, I think he would have rather been shot.
If you are put in an extreme situation, would you be FLIGHT or FIGHT?